The novel 8,14-secoursatriene derivative 6 was synthesized starting from ursolic acid (1) via methyl esterification of the 17-carboxylic acid group and benzoylation of the 3-hydroxy group (! 2; Scheme 1), ozone oxidation of the C(12)¼C(13) bond (! 3), dehydrogenation with Br 2 /HBr (! 4), enol acetylation of the resulting carbonyl group (! 5; Scheme 2), and ring-C opening with the aid of UV light (! 6). Ring-C-opened dienone derivative 7 of ursolic acid was also obtained via selective hydrolysis of 6 (Scheme 2). Both compounds 6 and 7 are key intermediates for the preparation of chiral decalin synthons from ursolic acid.
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